No matter how big they get, they’ll always be a little sibling
I bet it’s a point of pride for Raph that he can so easily cart his brothers around, no matter how big they get! It’s so cute how they use him like a jungle gym. The unmade episode where it showed how close he and Mikey once were leaves a bit of a bittersweet feeling that really hits home for someone who also was close to their oldest sibling in a way much different than we are now.
When I was little I was so used to just being hauled around like a sack of flour, be it by my parents or siblings, that I would constantly ask to be carried everywhere. This is particularly inspired by my oldest sister, who would do strength training by carrying me on her back on hikes alongside her weighted equipment. Absolute madwoman.
Imagine some bad guy gets the upper hand, but Raph just lets his brothers off his shell like Goku taking off his training weights and punches them to oblivion lol